Neurosurgery Blog

Neurosurg Focus 34 (4):E3, 2013

Navigated transcranial magnetic stimulation (nTMS) is a novel technology in the field of neurosurgery for noninvasive delineation of cortical functional topography. This study addresses the spatial accuracy and clinical usefulness of nTMS in brain tumor surgery in or near the motor cortex based on a systematic review of observational studies.

Methods. A systematic search retrieved 11 reports published up to October 2012 in which adult patients were examined with nTMS prior to surgery. Quality criteria consisted of documentation of the influence of nTMS brain mapping on clinical decision making in a standardized prospective manner and/or performance of intraoperative direct electrical stimulation (DES) and comparison with nTMS results. Cross-observational assessment of nTMS accuracy was established by calculating a weighted mean distance between nTMS and DES.

Results. All studies reviewed in this article concluded that nTMS correlated well with the “gold standard” of DES. The mean distance between motor cortex identified on nTMS and DES by using the mean distance in 81 patients described in 6 quantitatively evaluated studies was 6.18 mm. The nTMS results changed the surgical strategy based on anatomical imaging alone in 25.3% of all patients, based on the data obtained in 87 patients in 2 studies.

Conclusions. The nTMS technique spatially correlates well with the gold standard of DES. Its functional information benefits surgical decision making and changes the treatment strategy in one-fourth of cases.

Neurosurg Rev (2013) 36:321–330

Surgical access to deep intracranial lesions causing the least amount of iatrogenic trauma to the surrounding brain tissue remains a challenging task. In this article, we evaluate the use of a set of sequential tubes that dilate and provide retraction of the overlying brain tissue acting as a surgical corridor for deep-seated brain lesions resection. In addition, we conducted a comprehensive review of the literature of previously described techniques using variable brain tubular retractor systems. We discuss the adaptation of a system designed for spinal use to intracranial pathologies and evaluate the outcomes for the patients involved in the study. Moreover, the advantages and limitations of the described technique were presented.

Between August 2005 and 2011, a total of 30 patients with deep brain lesions were operated on using an incremental increase of tubing size for brain retraction guided by a frameless navigation device. Of these, seven cases were intraventricular, and 23 were intraparenchymal. Gross total resection was achieved in 70 % of cases, and the remaining had planned subtotal resections due to involvement of an eloquent area.

In conclusion, the technique of serial dilatation of the brain tissue can be used in conjunction with a microscope or endoscope to provide satisfactory access to deep intracranial pathologies. It appears to minimize the associated retraction injury to the surrounding tissue by gradually dilating the white fiber tracts. This operative approach may be considered as an effective and safe alternative for brain tumor resections in selected cases, especially deep-seated lesions.

A low triiodothyronine (T3) state is highly prevalent and is associated with a poor prognosis in critically ill patients. The authors investigated, in patients undergoing brain tumor surgery, the direct association of a perioperative low T3 syndrome with clinical outcomes and also with symptoms of depression and anxiety.

Methods. Ninety consecutive patients (71% women, median age 55 years), on admission for brain tumor surgery, were evaluated for sociodemographic and clinical characteristics. Their thyroid function profile was assessed on the morning of brain tumor surgery and on the morning after brain tumor surgery. Patients with free T3 concentrations of 3.1 pmol/L or less were considered to have low T3 syndrome. The patients were evaluated for symptoms of depression and anxiety using the Hospital Anxiety and Depression Scale (HADS) before and after surgery and for clinical outcomes using the Glasgow Outcome Scale (GOS) at discharge.

Results. After brain tumor surgery, free T3 concentrations decreased (p < 0.001) and the proportion of patients with low T3 levels increased from 38% to 54% (p = 0.02). Lower preoperative (rho = 0.30, p = 0.004) and postoperative (rho = 0.33, p = 0.002) free T3 concentrations correlated with low GOS scores at discharge. Preoperative low T3 syndrome (OR 5.49, 95% CI 1.27–23.69, p = 0.02) and postoperative low T3 syndrome (OR 8.73, 95% CI 1.49–51.21, p = 0.02) both increased risk for unfavorable clinical outcomes (GOS scores < 5) at discharge, after adjusting for age, sex, histological diagnosis of brain tumor, preoperative functional impairment, previous treatment for brain tumor, and depressive symptoms. Preoperative low T3 syndrome increased the risk for preoperative (HADS-depression subscale score ≥ 11; OR 4.12, 95% CI 1.16–14.58, p = 0.03) but not postoperative depressive symptoms independently from sociodemographic and clinical factors.

Conclusions. Low T3 syndrome is a strong independent predictor of unfavorable clinical outcomes and depressive symptoms, and its diagnosis and preoperative management should be considered in patients undergoing neurosurgery for the treatment of brain tumors.

J Neurosurg 118:521–529, 2013

It has been over a decade since the introduction of the da Vinci Surgical System into surgery. Since then, technology has been advancing at an exponential rate, and newer surgical robots are becoming increasingly sophisticated, which could greatly impact the performance of surgery. NeuroArm is one such robotic system.

Methods. Clinical integration of neuroArm, an MR-compatible image-guided robot, into surgical procedure has been developed over a prospective series of 35 cases with varying pathology.

Results. Only 1 adverse event was encountered in the first 35 neuroArm cases, with no patient injury. The adverse event was uncontrolled motion of the left neuroArm manipulator, which was corrected through a rigorous safety review procedure. Surgeons used a graded approach to introducing neuroArm into surgery, with routine dissection of the tumor-brain interface occurring over the last 15 cases. The use of neuroArm for routine dissection shows that robotic technology can be successfully integrated into microsurgery. Karnofsky performance status scores were significantly improved postoperatively and at 12-week follow-up.

Conclusions. Surgical robots have the potential to improve surgical precision and accuracy through motion scaling and tremor filters, although human surgeons currently possess superior speed and dexterity. Additionally, neuroArm’s workstation has positive implications for technology management and surgical education. NeuroArm is a step toward a future in which a variety of machines are merged with medicine.

Neurosurgery 70[ONS Suppl 2]:ons192–ons201, 2012 DOI: 10.1227/NEU.0b013e31823583a1

The middle fossa approach and extended middle fossa approach, also known as the anterior transpetrosal approach, are cranial base techniques for addressing small vestibular schwannomas, medial temporal bone lesions, midbasilar trunk aneurysms, and selected petroclival lesions.

OBJECTIVE: To provide an outline of a number of technical nuances that are important to correct application of these approaches, maximizing exposure, and limiting potential morbidity.

METHODS: Via a temporal craniotomy, the petrous apex is removed in variable degrees, depending on the exposure requirements of the lesion. The technique is described in detail with appropriate nuances of the technique provided.

RESULTS: The described nuances of technique in the performance of the approaches have resulted in successful application of these techniques in a significant number of cases.

CONCLUSION: Significant familiarity and practice with these surgical approach techniques are critical to applying them safely to clinical problems. A number of technical details can assist the surgeon in achieving optimal exposure and limited morbidity.

Acta Neurochir (2012) 154:585–588. DOI 10.1007/s00701-012-1290-8

Frameless stereotactic biopsies are replacing frame-based stereotaxy as a diagnostic approach to brain lesions. In order to avoid a sampling bias or negative histology, multiple specimens are often taken. This in turn increases the risk of hemorrhagic complications.

Objective We present the use of 5-aminolevulinic acid (5- ALA)-induced protoporphyrin IX fluorescence in frameless stereotaxy to improve the procedure duration and yield, and thereby reduce the risk of complications.

Methods Patients with suspected high-grade brain tumors are given 5-ALA 4 h prior to stereotactic biopsy. The biopsy needle is guided to the target using frameless stereotaxy based either on preoperative images or combined with intraoperative MRI sequences. The specimen is illuminated with blue light to look for fluorescence. In case of a positive fluorescence within the tissue sample, no frozen sections are obtained, and no further specimens are taken.

Results The samples of 13 patients revealed a positive fluorescence and were histologically confirmed as malignant or high-grade brain neoplasms. four cases were fluorescence-negative, requiring frozen section confirmation and/or multiple samples. In theses cases histology was either nonspecific gliotic changes or low-grade tumors. There were no complications related to the additional use of 5-ALA.

Conclusion 5-ALA fluorescence in stereotactic biopsies can increase the safety and accuracy of these procedures by reducing sampling errors and eliminating the need for multiple samples and/or frozen section verification, creating a more accurate, faster and safer procedure for cases of suspected malignant or high-grade brain tumors situated in deep or eloquent areas.

Neurosurgery 69[ONS Suppl 1]:ons49–ons63, 2011 DOI: 10.1227/NEU.0b013e3182155a52

Effective hemostasis is mandatory for brain tumor surgery. Microporous polysaccharide hemosphere (MPH) powder, a white powder compounded from potato starch, was recently introduced for surgical and emergency application.

OBJECTIVE: To evaluate the safety and efficacy of MPHs in brain tumor surgery.

METHODS: Thirty-three patients (mean age, 58 years; range, 22-84 years) underwent microsurgical brain tumor resection. Final hemostasis was performed by topical application of MPHs, video recorded, and subsequently analyzed. Blood samples were taken before surgery, before application of hemospheres, and postoperatively. Volume measurements of the tumor, resection cavity, and postoperative hematoma were done on magnetic resonance imaging and computed tomography scans. Clinical examinations focused on neurological outcome, complications, and allergic reactions.

RESULTS: Effective hemostasis was achieved by exclusive use of MPHs in 32 patients. In 1 patient, a single arterial bleeding underwent additional bipolar electrocauterization. Mean operative time was 156.8 minutes (range, 60-235 minutes). Hemostasis with MPHs required 57 seconds (mean; range, 8-202 seconds). Subjective neurosurgeons’ ranking of the hemostasis effect indicated excellent satisfaction. For the first 3 months, there was no hemospheres-related postoperative neurological worsening, no signs of allergic reaction, and no embolic complications. Early postoperative and 3-month follow-up magnetic resonance imaging and computed tomography scans excluded any expansive bleeding complication. As early as postoperative day 1, MPHs were no longer detected. There was no tumor mimicking contrast enhancement.

CONCLUSION: In neurosurgery, MPHs allow fast and effective minimally invasive hemostasis. In this small case series, no adverse reactions were found.

Neurosurgery 69:581–589, 2011 DOI: 10.1227/NEU.0b013e3182181b89

Transcranial magnetic stimulation (TMS) is the only noninvasive method for presurgical stimulation mapping of cortical function. Recent technical advancements have significantly increased the focality and usability of the method.

OBJECTIVE: To compare the accuracy of a 3-dimensional magnetic resonance imaging– navigated TMS system (nTMS) with the gold standard of direct cortical stimulation (DCS).

METHODS: The primary motor areas of 20 patients with rolandic tumors were mapped preoperatively with nTMS at 110% of the individual resting motor threshold. Intraoperative DCS was available from 17 patients. The stimulus locations eliciting the largest electromyographic response in the target muscles (‘‘hotspots’’) were determined for both methods.

RESULTS: The nTMS and DCS hotspots were located on the same gyrus in all cases. The mean 6 SEM distance between the nTMS and DCS hotspots was 7.83 6 1.18 mm for the abductor pollicis brevis (APB) muscle (n = 15) and 7.07 6 0.88 mm for the tibialis anterior muscle (n = 8). When a low number of DCS stimulations was performed, the distance between the nTMS and DCS hotspots increased substantially (r = 20.86 for APB). After the exclusion of the cases with , 15 DCS APB responses, the mean 6 SEM distance between the hotspots was only 4.70 6 1.09 mm for APB (n = 8).

CONCLUSION: Peritumoral mapping of the motor cortex by nTMS agreed well with the gold standard of DCS. Thus, nTMS is a reliable tool for preoperative mapping of motor function.

Acta Neurochir (2011) 153:1487–1495. DOI 10.1007/s00701-011-1046-x

Videoangiography using indocyanine green (ICG) has been used in the ophthalmologic field for a long time. It was introduced to the neurosurgical field several years ago but has been limited to vascular surgeries. We applied ICG videoangiography to brain tumor surgery and evaluated the usefulness.

Methods Twenty-three patients with a brain tumor who underwent microsurgical resection were analyzed. The pathological diagnosis was meningioma in 15 patients, metastasis in three, glioma in three, and hemangioblastoma in two. A microscope with a special filter and infrared excitation light to illuminate the operating field was used in this study. The intravascular fluorescence was imaged with a video camera attached to the microscope. ICG was injected intravenously with the dose of 5–25 mg, and overall, ICG was injected intraoperatively 32 times.

Results ICG videoangiography allowed for an excellent evaluation of blood flow in the tumoral and peri-tumoral vessels both before and after the resection in all cases.

Conclusions ICG videoangiography is a useful method for monitoring blood flow in the exposed vessels during microsurgery for a brain tumor. This noninvasive method is simple, safe, cost-effective, and easily repeatable. Before resection, it provides information on the tumoral and peritumoral circulation including sequential visualization of vessels or direction of the blood flow. After resection, it checks the patency of the peri-tumoral vessels and is especially useful for the vein. This ICG videoangiography can be an alternative tool to intraoperative angiography or Doppler ultrasonography in selective cases.

J Neurosurg 115:11–17, 2011. DOI: 10.3171/2011.2.JNS101451

Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative fluorescence of protoporphyrin IX (PpIX), synthesized endogenously following d-aminolevulinic acid (ALA) administration, has been used for this purpose in high-grade glioma (HGG). The authors show that diagnostically significant but visually imperceptible concentrations of PpIX can be quantitatively measured in vivo and used to discriminate normal from neoplastic brain tissue across a range of tumor histologies.

Methods. The authors studied 14 patients with diagnoses of low-grade glioma (LGG), HGG, meningioma, and metastasis under an institutional review board–approved protocol for fluorescence-guided resection. The primary aim of the study was to compare the diagnostic capabilities of a highly sensitive, spectrally resolved quantitative fluorescence approach to conventional fluorescence imaging for detection of neoplastic tissue in vivo.

Results. A significant difference in the quantitative measurements of PpIX concentration occurred in all tumor groups compared with normal brain tissue. Receiver operating characteristic (ROC) curve analysis of PpIX concentration as a diagnostic variable for detection of neoplastic tissue yielded a classification efficiency of 87% (AUC = 0.95, specificity = 92%, sensitivity = 84%) compared with 66% (AUC = 0.73, specificity = 100%, sensitivity = 47%) for conventional fluorescence imaging (p < 0.0001). More than 81% (57 of 70) of the quantitative fluorescence measurements that were below the threshold of the surgeon’s visual perception were classified correctly in an analysis of all tumors.

Conclusions. These findings are clinically profound because they demonstrate that ALA-induced PpIX is a targeting biomarker for a variety of intracranial tumors beyond HGGs. This study is the first to measure quantitative ALA-induced PpIX concentrations in vivo, and the results have broad implications for guidance during resection of intracranial tumors.

Neurosurgery 68[ONS Suppl 2]:ons282–ons290, 2011. DOI: 10.1227/NEU.0b013e318212464e

The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope.

OBJECTIVE: To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection.

METHODS: Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins.

RESULTS: Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microcopy—the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations.

CONCLUSION: Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

Childs Nerv Syst (2010) 26:19–28 DOI 10.1007/s00381-009-0990-8

This study described a 23-year experience in the treatment of children with pilocytic astrocytomas (piloA) with the aim of identifying putative clinical, histopathological, and/or immunohistochemical features that could be related to the outcome of these patients.

Methods Clinical data of 31 patients under 18 years of age with piloA were obtained from 1984 to 2006.

Results The mean age at the time of surgery was 7.8± 4.2 years (1 to 17 years), and the mean follow-up was 5.7± 5.4 years (1 to 20 years). The most common site of tumor formation was the cerebellum (17), followed by brainstem (4), optic chiasmatic hypothalamic region (4), cerebral hemisphere (3), cervical spinal cord (2), and optic nerve (1). Gross total resection (GTR) was achieved in 23 (74.1%), mainly in those with tumors located in the cerebellum and cerebral hemispheres (P=0.02). The global mortality rate was 6.4%. Nine patients were reoperated. Rosenthal fibers, eosinophilic granular bodies, microvascular proliferation, and lymphocytic infiltration were observed in most cases. The mean Ki-67LI was 4.4 ± 4.5%. In all cases, Gal-3 expression in tumor cells was observed with variable staining pattern.

Conclusions Aside from GTR, no other clinical, histopathological, or immunohistochemical features were found to be related to the prognosis. We postulate that strict follow- up is recommended if piloA is associated with high mitotic activity/Ki67-LI, or if GTR cannot be achieved at surgery. Tumor recurrence or progression of the residual lesion should be strictly observed. In some aspects, childhood piloA remains an enigmatic tumor.

Neurosurgery 65:908–913, 2009 DOI: 10.1227/01.NEU.0000356982.82378.BA

Magnetic resonance spectroscopy is widely used in addition to magnetic resonance imaging in the characterization of brain tumors. Compounds containing choline (Cho) have an important role in the evaluation of tumor malignancy. For this purpose, various ratios of Cho and other metabolites, such as creatine (Cr), have been assessed. The aim of this study was to compare normalized mean and maximum levels of Cho as single parameters in the noninvasive grading of gliomas.

METHODS: Proton spectroscopic imaging data of 63 patients with suspected World Health Organization (WHO) grade II or III gliomas were acquired at 3 T. Cho concentrations of the tumor were analyzed by a frequency domain fit and normalized to the corresponding contralateral healthy brain tissue. Metabolite images were used to determine the maximum and mean Cho as well as Cr concentrations of the tumor. Furthermore, contrast enhancement of the tumor was analyzed on standard magnetic resonance imaging. All patients subsequently underwent tumor resection or stereotactic biopsy to confirm diagnosis of glioma. Statistical analysis using the Kruskal-Wallis test, Mann-Whitney U test, and receiver operating characteristic curve analysis was performed with BiAS software (Epsilon Verlag GmbH, Frankfurt, Germany).

RESULTS: Histopathological examinations revealed WHO grades II (n=27), III (n=26), and IV (n=10). There was a statistically significant difference in both normalized maximum and mean Cho between WHO grade II and non-necrotic WHO grade III/IV gliomas (mean, 1.45 ^±0.28 versus 2.16±0.36, P<0.05; maximum, 1.64±0.32 versus 3.32±0.55, P<0.0001). Receiver operating characteristic analyses rendered a 2.02 cutoff value for maximum Cho with a sensitivity and specificity of 86.1% and 77.8%, respectively. For mean Cho, we found a cutoff value of 1.52 (sensitivity, 77.8%; specificity, 63.0%). The diagnostic accuracy of maximum Cho was superior to that of mean Cho and also the ratio of Cho/Cr (82.5% versus 71.4% and 72.1%, respectively), but all 3 parameters were superior to contrast enhancement of the tumor (61.9%).

CONCLUSION: Both maximum and mean Cho differ between low- and high-grade gliomas. Compared with contrast enhancement, mean Cho, and Cho/Cr, maximum Cho of the tumor provides the highest accuracy in discriminating between low- and high-grade tumors, indicating usefulness of this single parameter in the process of therapeutic decision making.

Journal of Clinical Oncology. DOI:10.1200/JCO.2008.19.8721

Purpose

We evaluated the efficacy of bevacizumab (Avastin TM), alone and in combination with irinotecan, in patients with recurrent glioblastoma in a phase II, multicenter, open-label, noncomparative trial.

Patients and Methods

One hundred sixty-seven patients were randomly assigned to receive bevacizumab 10 mg/kg alone or in combination with irinotecan 340 mg/m2 or 125 mg/m2 (with or without concomitant enzyme-inducing antiepileptic drugs, respectively) once every 2 weeks. Primary end points were 6-month progression-free survival and objective response rate, as determined by independent radiology review. Secondary end points included safety and overall survival.

Results

In the bevacizumab-alone and the bevacizumab-plus-irinotecan groups, estimated 6-month progression-free survival rates were 42.6% and 50.3%, respectively; objective response rates were 28.2% and 37.8%, respectively; and median overall survival times were 9.2 months and 8.7 months, respectively. There was a trend for patients who were taking corticosteroids at baseline to take stable or decreasing doses over time. Of the patients treated with bevacizumab alone or bevacizumab plus irinotecan, 46.4% and 65.8%, respectively, experienced grade  3 adverse events, the most common of which were hypertension (8.3%) and convulsion (6.0%) in the bevacizumab-alone group and convulsion (13.9%), neutropenia (8.9%), and fatigue (8.9%) in the bevacizumab-plus-irinotecan group. Intracranial hemorrhage was noted in two patients (2.4%) in the bevacizumab-alone group (grade 1) and in three patients (3.8%) patients in the bevacizumabplus-irinotecan group (grades 1, 2, and 4, respectively).

Conclusion

Bevacizumab, alone or in combination with irinotecan, was well tolerated and active in recurrent glioblastoma.

J Neurosurg Pediatrics 4:199-216, 2009. DOI: 10.3171/2009.3.PEDS08459

Object. The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable  epilepsy.
Methods. The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative   electroencephalography (EEG), MRimaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores.
Results. There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis.
Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3–6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child’s age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024).
Conclusions. Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

Neurosurg Rev (2009) 32:435–444.DOI:10.1007/s10143-009-0210-8

Trigeminal neurinomas are the second most common intracranial neurinomas next to the vestibular neurinomas. Eighty-four patients with trigeminal neurinomas were treated between 2003 and 2007. There were 40 women and 44 men (mean age 43 years). The most frequent symptoms were headache or numbness of the ipsilateral hemiface. There were 24 type A, nine type B, 45 type C, and six type D tumors. Dextroscope virtual reality technology was used for preoperative planning in recent eight cases. Gross total resection was achieved in 63 patients. We found that the major impediments to complete removal were adherent to the brainstem and skull base vascular structure, the frontotemporal approach with zygomatic or orbitozygomatic osteotomy or subtemporal approach could offer excellent exposure of the middle fossa and access to the posterior fossa, and Dextroscope virtual reality technology was a very useful tool to identify surgical and anatomic nuances and enhance preoperative planning in trigeminal neurinomas resection.

Vini G. Khurana, PhD, FRACS, Charles Teo, MBBS, FRACS, Michael Kundi, PhD, Lennart Hardell, MD, PhD, Michael Carlberg, MSc.

Surgical Neurology Volume 72, Issue 3, Pages 205-214 (September 2009) doi:10.1016/j.surneu.2009.01.019

The debate regarding the health effects of low-intensity electromagnetic radiation from sources such as power lines, base stations, and cell phones has recently been reignited. In the present review, the authors attempt to address the following question: is there epidemiologic evidence for an association between long-term cell phone usage and the risk of developing a brain tumor? Included with this meta-analysis of the long-term epidemiologic data are a brief overview of cell phone technology and discussion of laboratory data, biological mechanisms, and brain tumor incidence.

In order to be included in the present meta-analysis, studies were required to have met all of the following criteria: (i) publication in a peer-reviewed journal; (ii) inclusion of participants using cell phones for ≥10 years (ie, minimum 10-year “latency”); and (iii) incorporation of a “laterality” analysis of long-term users (ie, analysis of the side of the brain tumor relative to the side of the head preferred for cell phone usage). This is a meta-analysis incorporating all 11 long-term epidemiologic studies in this field.

The results indicate that using a cell phone for ≥10 years approximately doubles the risk of being diagnosed with a brain tumor on the same (“ipsilateral”) side of the head as that preferred for cell phone use. The data achieve statistical significance for glioma and acoustic neuroma but not for meningioma.

Conclusion

The authors conclude that there is adequate epidemiologic evidence to suggest a link between prolonged cell phone usage and the development of an ipsilateral brain tumor.

In elderly patients with brain tumors, the prevention of postoperative systemic complications is extremely important, and identification of the risk factors would be useful for planning therapy. The authors investigated ways to avoid postoperative complications by identifying risk factors.

Methods
The study population included 84 patients, 70 years of age or older, who underwent surgical brain tumor removal. The following independent factors were assessed by univariate and multivariate analyses: sex, age, preoperative underlying diseases and complications, histopathological findings, preoperative Karnofsky Performance Scale (KPS) score, preoperative whole blood hemoglobin (Hb) level, preoperative serum total protein (TP) level, operation time, intraoperative blood loss, change in Hb level (difference between pre- and postoperative values), and change in TP level (difference between pre- and postoperative values). The cutoff values for significant independent factors were also determined.

Results
Overall, 35 (41.7%) of the 84 patients had a total of 56 postoperative systemic complications. Univariate analysis identified the preoperative KPS score, intraoperative blood loss, change in Hb level, and change in TP level as risk factors for postoperative complications, and multivariate analysis extracted the following risk factors: the preoperative KPS score (p = 0.0450, OR 4.020), intraoperative blood loss (p = 0.0104, OR 6.571), and change in Hb levels (p = 0.0023, OR 9.301). The cutoff values were: KPS score < 80%, intraoperative blood loss ≥ 350 ml, and change in Hb level ≥ 2.0 g/dl.

Conclusions
In elderly patients with brain tumors, low preoperative KPS score, high intraoperative blood loss, and a large difference between pre- and postoperative Hb levels are significant risk factors for postoperative systemic complications.